Involvement of Sp1 binding sequences in basal transcription of the rat fibroblast growth factor-2 gene in neonatal cardiomyocytes

Role of Specificity Protein 1 (SP1) in Cardiovascular Diseases: Pathological Mechanisms and Therapeutic Potentials

In mammals, specificity protein 1 (SP1) was the first Cys2-His2 zinc finger transcription factor to be isolated within the specificity protein and Krüppel-like factor (Sp/KLF) gene family. SP1 regulates gene expression by binding to Guanine-Cytosine (GC)-rich sequences on promoter regions of target genes, affecting various cellular processes. Additionally, the activity of SP1 is markedly influenced by posttranslational modifications, such as phosphorylation, acetylation, glycosylation, and proteolysis. SP1 is implicated in the regulation of apoptosis, cell hypertrophy, inflammation, oxidative stress, lipid metabolism, plaque stabilization, endothelial dysfunction, fibrosis, calcification, and other pathological processes. These processes impact the onset and progression of numerous cardiovascular disorders, including coronary heart disease, ischemia-reperfusion injury, cardiomyopathy, arrhythmia, and vascular disease. SP1 emerges as a potential target for the prevention and therapeutic intervention of cardiac ailments. In this review, we delve into the biological functions, pathophysiological mechanisms, and potential clinical implications of SP1 in cardiac pathology to offer valuable insights into the regulatory functions of SP1 in heart diseases and unveil novel avenues for the prevention and treatment of cardiovascular conditions.

Small Extracellular Vesicle-Derived vWF Induces a Positive Feedback Loop between Tumor and Endothelial Cells to Promote Angiogenesis and Metastasis in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a hypervascular malignancy by which its growth and dissemination are largely driven by the modulation of tumor-derived small extracellular vesicles (sEVs). Proteomic profiling of circulating sEVs of control individuals and HCC patients identifies von Willibrand factor (vWF) to be upregulated progressively along HCC stages. Elevated sEV-vWF levels are found in a larger cohort of HCC-sEV samples and metastatic HCC cell lines compared to their respective normal counterparts. Circulating sEVs of late-stage HCC patients markedly augment angiogenesis, tumor-endothelial adhesion, pulmonary vascular leakiness, and metastasis, which are significantly compromised by anti-vWF antibody. The role of vWF is further corroborated by the enhanced promoting effect of sEVs collected from vWF-overexpressing cells. sEV-vWF modulates endothelial cells through an elevated level of vascular endothelial growth factor A (VEGF-A) and fibroblast growth factor 2 (FGF2). Mechanistically, secreted FGF2 elicits a positive feedback response in HCC via the FGFR4/ERK1 signaling pathway. The co-administration of anti-vWF antibody or FGFR inhibitor significantly improves the treatment outcome of sorafenib in a patient-derived xenograft mouse model. This study reveals mutual stimulation between HCC and endothelial cells by tumor-derived sEVs and endothelial angiogenic factors, facilitating angiogenesis and metastasis. It also provides insights into a new therapeutic strategy involving blocking tumor-endothelial intercellular communication.

Neurotrophic factor-α1 prevents stress-induced depression through enhancement of neurogenesis and is activated by rosiglitazone

Major depressive disorder is often linked to stress. Although short-term stress is without effect in mice, prolonged stress leads to depressive-like behavior, indicating that an allostatic mechanism exists in this difference. Here we demonstrate that mice after short-term (1 h per day for 7 days) chronic restraint stress (CRS), do not display depressive-like behavior. Analysis of the hippocampus of these mice showed increased levels of neurotrophic factor-α1 (NF-α1; also known as carboxypeptidase E, CPE), concomitant with enhanced fibroblast growth factor 2 (FGF2) expression, and an increase in neurogenesis in the dentate gyrus. In contrast, after prolonged (6 h per day for 21 days) CRS, mice show decreased hippocampal NF-α1 and FGF2 levels and depressive-like responses. In NF-α1-knockout mice, hippocampal FGF2 levels and neurogenesis are reduced. These mice exhibit depressive-like behavior that is reversed by FGF2 administration. Indeed, studies in cultured hippocampal neurons reveal that NF-α1 treatment directly upregulates FGF2 expression through extracellular signal-regulated kinase-Sp1 signaling. Thus, during short-term CRS, hippocampal NF-α1 expression is upregulated and has a key role in preventing the onset of depressive-like behavior through enhanced FGF2-mediated neurogenesis. To evaluate the therapeutic potential of this pathway, we examined, rosiglitazone (Rosi), a PPARγ agonist, which has been shown to have antidepressant activity in rodents and humans. Rosi upregulates FGF2 expression in a NF-α1-dependent manner in hippocampal neurons. Mice fed Rosi show increased hippocampal NF-α1 levels and neurogenesis compared with controls, thereby indicating the antidepressant action of this drug. Development of drugs that activate the NF-α1/FGF2/neurogenesis pathway can offer a new approach to depression therapy.

Mitogen-activated protein kinases ERK 1/2- and p38-GATA4 pathways mediate the Ang II-induced activation of FGF2 gene in neonatal rat cardiomyocytes

Several genes, including fibroblast growth factor 2 (FGF2), are up-regulated in the hypertrophic heart. However, the molecular mechanisms responsible for the angiotensin II (Ang II)-induced activation of FGF2 in cardiomyocyte hypertrophy are largely unknown. The purpose of this study was to determine the signaling cascades underlying the Ang II-induced transcriptional activation of FGF2 in neonatal rat cardiomyocytes. Real-time quantitative RT-PCR and Western blot showed that Ang II upregulates FGF2 expression and that these effects were attenuated by U0126 or SB203580, but not by SP600125. Deletion analyses revealed that the region between -845 and -666 is essential for Ang II-induced FGF2 promoter activity. The existence of an atypical GATA4-binding motif, located at position -752, was identified using electrophoretic mobility shift assay (EMSA). Using both EMSA and chromatin immunoprecipitation (ChIP) analyses, we also showed that Ang II increases binding of GATA4 to DNA, and that this effect is attenuated in the presence of U0126 or SB203580, but not in the presence of SP600125. GATA4 siRNA significantly reduced Ang II-induced FGF2 mRNA levels. Together, these results indicate that binding of GATA4 to DNA is increased by Ang II via extracellular signal-regulated protein kinase 1/2 (ERK 1/2) and p38 kinase, which increases FGF2 gene expression in neonatal rat cardiomyocytes.